I think he's just playing the game as the rules are written right now. He doesn't have to like patents to know that they are currently one of the best ways to protect himself. I'm not a fan of the current system, but if I found myself in a similar position, I'd certainly review my options as well.

I'm not sure what you mean by protect himself here. What does he protect himself from?

If you mean he protects himself from people 'taking' his idea, then he clearly doesn't hate software patents because that's what they achieve. What do you hate about them if you want this protection?

If you mean he protects himself from someone else patenting the same idea, filing a patent doesn't do this. As long as he has his ducks in a row to demonstrate that his work constitutes prior art (which he might have to do anyways if, say facebook comes out and tries to patent what sounds like a similar idea). Realistically, the odds that, against a larger competitor, he wouldn't have to go through the same process either way (a legal battle and/or settlement) seem strikingly low to me.

If you mean he can play the defensive patent shell game and cross-license to settle, one patent won't really do that unless you pool in with an NPE that collects patents, and that also seems rather contrary to the idea of hating software patents.